Skimbleshanks, aka Skimble, is the orange Railway Cat. He's one of the feline inhabitants of London and one of the most important characters, appearing in almost all Sheldon and His Jellicles stories.
In Sheldon and His Jellicles[]
As an addition to his character, he likes his train and does whatever he can to protect it from other animals such as mice and rats. He gets cross and grumpy when they try to destroy his train.
Traditionally, the musical adaptation of Skimble’s fur is usually orange, but on The New Adventures of Bustopher Jones his fur color is more tannish than usual, perhaps unintentionally. This tan tint also happened in Bustopher Jones and Tugger Too.
Though Skimble is a living animal, the episode of The New Adventures of Bustopher Jones titled "How Much is That Railway Cat in the Window" contradicts this, in which Skimble runs away - thinking the others have forgotten his birthday. He is picked up by a peddler, put in a store, and sold back to Sheldon. As Skimble was not put in a cage, we can assume, at least in this episode, that he was stuffed. This is probably just a one time thing, as most of the episodes aren't particularly canon with each other.
Skimble through Priya and Sheldon's eyes.